The proposal covers the collection of high resolution native and heavy atom cluster data for RNA-Polymerase II from yeast. RNA-Polymerase II is responsible for the transcription from DNA to RNA of virtually all of the proteins in eukaryotes. There are now a number of co-crystals, with RNA, DNA, RNA+DNA, amanitin (an inhibitor) and promising heavy atom cluster compounds. Because a single data collection can take 36-40 hours, we have requested a large amount of beam time; however, given the unit cell size and the brightness of the source, the data collections cannot be accomplished in less time. It is expected that as the diffraction to higher resolution improves, more time may be needed, as the data will require two or more sweeps.